1. Technical Field
The present invention relates to FETs (Field Effect Transistors), and more specifically, to double-gate FETs.
2. Related Art
Dopant fluctuations are becoming a serious problem in Vt (threshold voltage) control in advanced semiconductor devices. As semiconductor devices become smaller and smaller in size, Vt control becomes more difficult. A known solution is to use back gates (in addition to front gates) in the semiconductor devices to control Vt. By adjusting the voltage applied to the back gates, Vt of devices can be adjusted (i.e., controlled). However, back gates occupy chip areas, and as a result, device density is reduced.
As a result, there is a need for a device structure (and method for forming the same), in which chip areas for back gates are relatively small compared to the prior art.